1996 KANSAS WATER QUALITY ASSESSMENT (305(b) REPORT)

December 1996

Kansas Department of Health and Environment, Division of Environment
Bureau of Environmental Field Services
1000 SW Jackson, Topeka, KS 66612

Table of Contents - Part I - Part II - Part III - Part IV - References - Appendix

PART IV: GROUNDWATER ASSESSMENT

Much of Kansas is underlain by porous geological formations containing appreciable quantities of groundwater. The largest such formations consist of unconsolidated materials (gravel, sand, and silt) deposited by streams. Some unconsolidated glacial deposits and consolidated bedrock formations also contain appreciable quantities of groundwater. The total freshwater storage in all major Kansas aquifers is estimated at 590 million acre-feet.

Groundwater resources are relatively abundant in the western two-thirds of the state where surface water is scarce. Groundwater resources are limited in the eastern one-third of Kansas where surface water is more plentiful. Ninety percent of all water use within the state is supplied from groundwater. Irrigation continues to account for the greatest consumptive use of this resource.

A total of 637 community public water supplies are dependent on groundwater, either solely or in combination with surface water sources. These supplies serve a total population of 1,717,464. In most rural areas, groundwater provides the primary source of drinking water.

Groundwater quality in most of the state is generally sufficient to maintain existing uses. The mineral content of the soil and rock formations in which groundwater is found causes the water to be quite hard (greater than 200 mg/L as calcium carbonate). Groundwater quality problems are generally site-specific. A few of these site specific problems are the result of natural source contamination, but usually the contamination is due to human activities. The Kansas Department of Health and Environment is cognizant of over 500 isolated groundwater pollution problems not including Leaking Underground Storage Tanks (LUST) sites.

Groundwater Monitoring Program

The department’s groundwater quality monitoring network is the primary ambient groundwater program in Kansas. Public water supply wells are monitored by KDHE's Bureau of Water (BOW) for compliance with state and federal drinking water standards. Additional monitoring is done in intensive groundwater usage areas by five groundwater management districts (GMDs).

A statewide Wellhead Protection Program (WHPP) was recently approved by EPA. At least three Kansas counties are in the process of developing or establishing local WHPP plans and several other communities in the state have expressed interest and/or have started collecting information about forming local WHPPs. The City of Hays already has adopted a local WHPP.

Numerous other state programs have been established or are in the developmental stages to assist in groundwater protection and pollution prevention (Table 34).

Table 34. Summary of State Groundwater Protection Programs

*principal administrative agency

Groundwater Quality Monitoring Network

The Kansas groundwater quality monitoring network (Figure 9), established in 1976 as a cooperative program between USGS and KDHE, is the principal statewide groundwater quality monitoring effort. In 1990, KDHE assumed sole responsibility for the monitoring network.

The primary goal of the network is to procure long-term, statewide groundwater quality data for use in the identification of temporal and spatial trends in groundwater quality associated with the following: (1) alterations in land use, (2) application of land treatment methods and other NPS best management practices, (3) changes in groundwater availability or withdrawal rates, and (4) variations in climatological conditions within the state. In addition, the network is intended to assist in the identification of groundwater contamination problems in Kansas.

The current (1995) Kansas groundwater quality monitoring network is composed of 242 wells including public water supply (PWS)(71%), irrigation (14%), rural-domestic (10%), multiple use (3%), livestock watering (1%), and industrial wells (1%). During the period 1991-1995, 628 well samples were analyzed for common inorganic chemicals and heavy metals; 490 well samples were analyzed for pesticides; 113 well samples were analyzed for volatile organic compounds (VOCs); and 124 well samples were analyzed for radionuclides (Appendix Part I.E.). Additionally, some of the network wells were also sampled by other programs.

Most wells were sampled more than once during this reporting period. Each network well is sampled for inorganics every other year. The wells chosen to be sampled each year for pesticides, VOCs, and radionuclides are rotated systematically throughout the network; five of the wells repeatedly sampled for radiation are located in southeastern Kansas because of known problems in that region. Beginning in 1993, an allotment of 10 radiation samples per year was also analyzed for radon.

In evaluating the data from 1991-1995, 126 instances were found in which the chemical quality of the raw groundwater samples exceeded federal drinking water Maximum Contaminant Levels (MCLs). Of these, 81 were due to nitrate exceedences. The occurrence of nitrate in groundwater is generally attributed to human activities (such as agricultural fertilizer applications, malfunctioning septic systems, etc.), natural conditions, or both.

Special Studies

In response to the "flood of 1993", CDC funded a systematic study of private water wells in Kansas and eight other midwest states to determine the extent of microbiological and/or chemical contamination of groundwater resulting from flood waters or subsequent high watertables. The department’s Division of Health implemented the Kansas portion of this multi-state study.

The surveyed wells were analyzed for total coliform bacteria, Escherichia coli, nitrate, atrazine, and lead. In addition to the collection of water samples, a questionnaire for each well was completed that covered the following topics: well construction, depth, age, location in relation to possible sources of contamination, demographic data, and health of the well users.

The results of this study indicated that certain types of wells, especially dug wells, are more susceptible to contamination. However, since the survey tested wells randomly derived from intersecting points on a map grid, samples were collected regardless of whether the well was properly constructed or sealed.

For this reason and because the samples were collected from a faucet inside the homes with minimal purging (lead samples were taken from the first flow), this study does not give a true representation of actual groundwater quality. Nevertheless, the study does provide useful insight concerning drinking water quality "at the tap" of typical rural-domestic well users in Kansas.

Major Causes and Sources of Groundwater Contamination

Based on the most recent available compilation by KDHE's Bureau of Environmental Remediation (BER), there are 645 documented contamination sites on the Identified Sites List (ISL) within the state, excluding sites under the jurisdiction of the Kansas Corporation Commission (KCC). Of these ISL sites, 120 were resolved leaving 525 active sites. The most common sources of contamination are operational problems at active facilities, spills, and leaking and/or overflowing lagoons (KDHE 1996).

Within recent years, BER has expanded the petroleum storage tank program which has uncovered several occurrences of groundwater contamination and has implicated leaking storage tanks as a significant source of groundwater contamination.

The Underground Petroleum Storage Tank Release Trust Fund was established to provide reimbursements to tank owners for corrective action costs. A total of 197 new site applications were received by the Fund in 1995.

Nonpoint sources of pollution comprise another major concern in Kansas; however, it is an extremely difficult issue to address due to the widespread nature of the problem. Nonpoint sources of groundwater contamination potentially include such things as agricultural activities, urban runoff, mining, application of residential lawn chemicals, highway deicing materials, feedlots, salvage yards, airports, golf courses, and many other factors.

Additionally, certain regions of the state have groundwater quality problems due, in part, to naturally occurring conditions. One example would be brine intrusion from underlying salt deposits in some areas. Table 35 lists a few of the most significant sources of groundwater contamination in the state based on the best professional judgement of KDHE staff.

Table 35. Major Sources of Groundwater Contamination

Nationally, the EPA has identified 1,245 contaminated sites that are included on the 1995 National Priorities List (NPL) and are targeted for cleanup under Superfund (EPA 1995b). Presently, there are twelve NPL sites located in Kansas. All but one of these 12 NPL sites are located in the eastern half of the state.

With the possible exception of the nitrate problem, most of the groundwater contamination occurs mainly as isolated situations due to human activity involving VOCs, heavy metals, and/or petroleum products. In a few areas, naturally occurring constituents, such as fluoride, selenium, and radionuclides, may locally exceed MCLs. A summary of all known groundwater contamination sites is presented in Table 36.

Summary of Groundwater Quality

Kansas groundwater is generally very hard (usually greater than 200 mg/L) and often contains relatively high concentrations of TDS, manganese, and iron. In some areas, elevated levels of ammonia, sulfate, sodium, and chloride also exist. These constituents normally do not cause health-related problems; however, they may create aesthetic problems such as scale deposits, stains, odor, and undesirable taste.

Nitrate contamination in groundwater is a major concern due to the many, widespread sources. Nitrate accounted for most instances in which federal drinking water MCLs were exceeded. During the period 1991-1995, excessive concentrations of nitrate (greater than 10 mg/L as N) were observed in approximately 12% of 681 well samples collected from the Kansas groundwater quality monitoring network (most wells were sampled more than once), compared to 14% during the period 1976-1981.

A majority of the well samples with excessive concentrations of nitrate during this reporting period were obtained from relatively shallow wells that were 100 feet or less in total depth. Wells located in areas of the state where the soils are extremely sandy and where the water table is relatively close to the surface have a greater chance of yielding higher nitrate levels. Water quality in most Kansas aquifers may be highly variable which makes definitive source assessment of nitrates difficult.

Groundwater contamination in Kansas is typically site-specific. Isolated groundwater pollution problems are occasionally due to natural sources, but more often are due to human activity or a combination of both. Despite these various documented problems, groundwater quality in the state is generally adequate to maintain present uses, if pollution prevention and groundwater protection practices continue to be implemented.

Table 36. Groundwater Contamination Summary. Statewide Summary for the Period of 1991-1995

CAPs - Corrective Action Plans
CERCLIS - Comprehensive Environmental Response, Compensation, and Liability Information System
DOD/DOE - Department of Defense/Department of Energy
LUST - Leaking Underground Storage Tanks
NPL - National Priority List
NPS - Non Point Source
RCRA - Resource Conservation and Recovery Act

* Represents Class I, III, and V injection wells, but does not include Class II brine injection wells.
** Numbers are for 1993 only and do not include sites under KCC jurisdiction

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